Project Summary The objective of the proposed research is to better characterize and understand functional vision processing deficits in cerebral/cortical visual impairment (CVI), the leading cause of congenital vision loss in the United States and developed world. Perinatal damage to developing visual pathways and structures leads to impaired visual spatial processing abilities, particularly in the setting of high environmental complexity and attention demands. Standard clinical assessments and traditional psychophysical stimuli fail to characterize these functional vision deficits due to their lack of ecological validity. To address this unmet need, we have developed a novel virtual reality (VR) based testing platform to assess visual spatial processing abilities in tasks that approach real world situations. In this cross-sectional behavioral study, performance in children and adolescents with CVI will be compared to age-matched ocular visual impaired (OVI) individuals as well as neuro-typical developed sighted controls. Using recorded eye tracking metrics, we will characterize visual search performance and the effect of manipulating stimulus factors in the VR environment. Our central hypothesis is that VR based assessment will reveal impairments in visual spatial processing that are not characterized by standard clinical assessments. In our first aim, we will compare visual spatial processing abilities using two VR based visual search tasks. The first is a static object visual search task (the ?virtual toy box?) in which participants must search for a toy positioned in an array of distractor elements (other toys). The second is a dynamic object visual search task (the ?virtual corridor?) in which participants must search for the principal of a school in a crowd of distractor elements (other individuals walking in a school corridor). In both tasks, visual search performance will be assessed by varying the number of surrounding distractor elements. We hypothesize that in contrast to individuals with OVI and sighted controls, CVI participants will show greater impairment in performance as a function of increasing visual task demands associated with environmental complexity. In the second aim, we will characterize the effect of manipulating environmental factors using the VR environment on spatial processing abilities. We hypothesize that compared to baseline performance, individuals with CVI will reveal improved performance when target saliency is enhanced, while manipulations that decrease overall target saliency and/or increase task complexity will be associated with impaired performance. The proposed work is of great significance given the potential for developing a novel and ecologically valid VR based platform that provides for superior assessment of visual functional deficits in individuals based on their type of visual impairment. Furthermore, this investigation will help lay the ground work for the creation of new adaptive tools and strategies designed for an individual's specific developmental and rehabilitative needs. This is of particular significance for individuals with CVI; a population that has been greatly underserved despite its important